Abstract: An optical mouse comprises an illumination system for converging light emitted from a light emitting element to a light pattern of a mouse pad, an image forming system for forming an image of the light pattern on the side of a light receiving element and an aspherical lens having a positive refractive index and formed with an aspherical surface in at least one surface thereof. The aspherical surface is used for the illumination system and/or the image forming system. In a preferred form, the aspherical lens is a single lens made of a synthetic resin for constituting the image forming system and satisfying the following optical conditions:2<.vertline..beta..vertline.<150.2<r.sub.1 .multidot.(n-1)/f-3<K.sub.2 <00.012<NA<0.18where .beta.=a magnificationr.sub.1 : a radius of curvature of a surface of the lens on the mouse pad side;n: the refractive index of lens material in wave length: 950 nm);f: a focal distanceK.sub.2 : a cone coefficient; andNA: the number of apertures.

Abstract: An optical mouse for inputting a cursor position including first and second line patterns formed on opposite surfaces of a transparent substrate, with the lines of the first and second line patterns being perpendicular. The line patterns are illuminated by a light source in the movable mouse body, which also includes an optical system and detecting elements for separately detecting light reflected from the first and second patterns. Because the first and second line patterns are located at different distances from the optical system, light reflected from the two patterns can be separately focused to prevent interference between the two patterns.